1. Field of the Invention.
This invention relates to an apparatus for generating and regulating currents of high intensity, especially welding currents, by phase section, with primary and secondary circuits connected through a transformer.
2. Description of the Prior Art.
In a welding appliance of conventional type, the intensity of the welding current is modified by means of tappings on the primary or choke coil by means of tap changers. Regulation of the welding currents by means of hand wheels or cranks, which are most clumsy in operation, is also known. It is further known to regulate welding currents by means of transductors (Ger. Pub. Sp. 1,116,331). Such apparatuses have the disadvantage of large components an high energy consumption. They further require high switch-on currents. As a result of the great construction size of the parts, transport of the apparatus is difficult. The measures known hitherto for the regulation of welding currents further have the disadvantage that operation is complicated and remote controlling is not possible in the case of mechanical regulation.
According to the phase position and premagnetisation of the transformer plate, very high magnetisation currents occur on switching on of the welding currents, which suddenly overload the transformer, mains and fuses of the apparatus.
At the beginning of the welding operation the electrodes are in contact with the welded material. This effects high short-circuit currents which exceed the maximum rated current, frequently by 50%. The connected load of the welding apparatus, the rated value of the fuses and the conductor cross-section must be designed accordingly, possibly over-dimensioned, in order to exclude danger due to over-heating.